If you must disassemble the bolt, it can be most easily done by first holding the rifle horizontally in a padded bench vise - after ensuring that the rifle is not loaded.
Insert the bolt into the action, as normal, and close the bolt handle (down) on the empty chamber.
The rifle should be now cocked & locked, with the cocking piece (around the rear end of the firing pin) in it's rearmost position, with a slight gap between it's forward edge and the inside edge of that rear bolt shroud (just below the little hole where the old safety was removed).
Insert a small, sacrificial, square-edged steel tool (screwdriver ?) in there to keep the firing pin, etc, wedged back while the bolt handle is then lifted and the bolt withdrawn rearward from the action.
The bolt internals may now be unscrewed from the main bolt body for a power flush & light lube - as well as the firing pin well inside the bolt body.
Assemble in reverse order.
As for cleaning the bore, I would first plug the muzzle with a disposable foam earplug, them set it in a quiet corner for at least one day with the bore & chamber poured full of Hoppe's #9 or somesuch cleaner, to let it really soak good before heavy bronze brushing session(s), followed by patches.
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